What are the diagnostic criteria for Idiopathic Intracranial Hypertension (IIH)?

From the Guidelines

Idiopathic intracranial hypertension (IIH) is diagnosed through a combination of clinical evaluation, neuroimaging, and lumbar puncture, with the presence of papilledema, normal neurological examination, normal brain imaging, elevated cerebrospinal fluid (CSF) pressure, and normal CSF composition being essential for diagnosis. The diagnosis of IIH requires a thorough clinical evaluation, including a detailed medical history and physical examination, to identify symptoms such as headache, visual disturbances, and pulsatile tinnitus 1.

Diagnostic Criteria

The modified Dandy criteria are commonly used diagnostic guidelines, which include:

• Presence of papilledema
• Normal neurological examination except for cranial nerve abnormalities
• Normal brain imaging without hydrocephalus or mass
• Elevated cerebrospinal fluid (CSF) pressure (≥250 mm H2O in adults or ≥280 mm H2O in children)
• Normal CSF composition

After initial clinical suspicion, an MRI with venography should be performed to rule out secondary causes of increased intracranial pressure, such as cerebral sinus thrombosis 2. A lumbar puncture is essential to measure opening pressure and analyze CSF composition. Visual field testing and optical coherence tomography are important to assess optic nerve function and monitor disease progression.

Investigation and Management

The investigation and management of IIH involve a multidisciplinary approach, including neurologists, ophthalmologists, neurosurgeons, radiologists, and other clinicians 3, 4. The target audience for the consensus guidelines includes clinicians who investigate and manage IIH, with the aim of increasing awareness and improving outcomes for patients. Early diagnosis is crucial as untreated IIH can lead to permanent vision loss, and patients typically present with obesity and are often young women of childbearing age, though IIH can occur in any demographic group.

Key Considerations

Key considerations in the diagnosis and management of IIH include:

• The importance of early diagnosis and treatment to prevent permanent vision loss
• The need for a multidisciplinary approach to investigation and management
• The use of modified Dandy criteria as diagnostic guidelines
• The importance of MRI with venography and lumbar puncture in the diagnostic workup
• The need for regular monitoring of optic nerve function and disease progression.

From the Research

IIH Diagnosis

• The diagnosis of Idiopathic Intracranial Hypertension (IIH) requires the modified Dandy criteria to be satisfied, which involves identifying or excluding multiple potential contributing causes of intracranial hypertension 5.
• The clinical presentation of IIH most often includes headaches and papilledema, but many other findings have been described, such as disturbance of vision, diplopia, and tinnitus 5, 6.
• Neuroradiological signs, such as those observed through optical coherence tomography, visual evoked potentials, ocular ultrasonography, and fundus fluorescein angiography and autofluorescence, can be useful in the diagnostic process, especially in patients who do not present papilloedema 6.
• Cerebrospinal fluid pressure measurement is required to establish a definite diagnosis of IIH 5, 6.

Diagnostic Criteria

• The diagnosis of IIH is based on the presence of increased intracranial pressure, typically measured through lumbar puncture, and the absence of an alternative cause 5, 7.
• The modified Dandy criteria include the following:
  • Increased intracranial pressure
  • Normal cerebrospinal fluid composition
  • No evidence of structural lesion or other cause of increased intracranial pressure
  • No other cause of increased intracranial pressure identified 5.

Diagnostic Challenges

• IIH remains an enigmatic diagnosis of exclusion, and prompt diagnosis and thorough evaluation and treatment are crucial for preventing visual loss and improving associated symptoms 5.
• The clinical presentation of IIH can be variable, and papilloedema may not be observed in all patients, making diagnosis more challenging 6.
• Other conditions, such as secondary pseudotumor syndromes, must be excluded before making a diagnosis of IIH 5.